When you use ethylene or propylene glycol or glycerine as solvent you must add alkali to the working solution. There are many possibilities. You don't say which, if any, you used. I never did try antifreeze without alkali. Perhaps some of the stuff that makes it green is alkaline enough to give some development.
You zeroed your densitometer on B+F, so the Zones that measured 0.4 surely can't be fog. They can oly be a mystery! Try using 1 tsp each of sodium carbonate and borax in a liter of water to dilute your glycol solution 1+50 for a quick and dirty test. This should give you a fairly linear plot from zones 2 on up with development of about 8 minutes at 70 F. If actual fog is too high for you, add some bromide to the working solution. I am not overly concerned about the fog I have seen, but if you use some of the alternative processes as Sandy does, double fog density means doubling an already very long exposure to UV light.
Keep in touch.